package com.hmdp.service.impl;


import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWord;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.util.Collections;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Slf4j
@Service
@Transactional
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Resource
    private ISeckillVoucherService iSeckillVoucherService;
    @Resource
    private RedisIdWord redisIdWord;
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);

    }


    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    @PostConstruct
    private void  init () {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }
    private class VoucherOrderHandler implements Runnable {

        @Override
        public void run() {
            while ( true){
                try {
                    VoucherOrder voucherOrder = orderTasks.take();
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                 log.error("处理订单异常", e);
                }
            }
        }
    }

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        String userId = voucherOrder.getUserId();
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        boolean isLock = lock.tryLock();
        if (!isLock) {
            log.error("不允许重复下单");
            return;
        }
        try {
            // ✅ 临时获取代理对象（线程安全）
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            // ✅ 调用新方法：createVoucherOrder(VoucherOrder)
            proxy.createVoucherOrder(voucherOrder);
        } catch (Exception e) {
            log.error("异步创建订单失败，订单: {}", voucherOrder, e);
            // TODO: 可记录到失败表，后续补偿
        } finally {
            lock.unlock();
        }
    }


    @Override
    public Result seckillVoucher(Long voucherId) {
        //1.执行lua脚本
        String userId = UserHolder.getUser().getId();
        Long result = stringRedisTemplate.execute(SECKILL_SCRIPT,
                //keys
                Collections.emptyList(),
                //values
                voucherId,
                userId
                //lua脚本的keys和values的索引
        );
        //2.判断
        int r = result.intValue();
        if (result != 0) {
            //2.1 ！0
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }


        VoucherOrder voucherOrder = new VoucherOrder();
        //2.1.生成订单ID
        Long orderId = redisIdWord.nextId("order");
        voucherOrder.setId(orderId);
        //2.2.生成用户ID
        voucherOrder.setUserId(userId);
        //2.3.生成代金券ID
        voucherOrder.setVoucherId(voucherId);
        //2.4 放入阻塞队列
        if (!orderTasks.offer(voucherOrder)) { // ← 建议用 offer 防队列满
            log.error("订单队列已满，用户: {}", userId);
            return Result.fail("系统繁忙，请稍后再试");
        }
        //3.返回订单ID
        return Result.ok(orderId);
    }

//    @Override
//    public Result seckillVoucher(Long voucherId) {
//        //1.查询
//        SeckillVoucher voucher = iSeckillVoucherService.getById(voucherId);
//        //2.判断秒杀是否开始
//        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
//            return Result.fail("秒杀尚未开始");
//        }
//        //3.判断秒杀是否结束
//        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
//            return Result.fail("秒杀已结束");
//        }
//        //4.判断库存是否充足
//        if (voucher.getStock() < 1) {
//            return Result.fail("库存不足");
//        }
//
//        String userId = UserHolder.getUser().getId();
//        //创建锁对象
//        // SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
//        RLock lock = redissonClient.getLock("lock:order:" + userId);
//
//        //获取锁
//        boolean isLock = lock.tryLock();
//        if (!isLock) {
//            //获取锁失败，返回失败
//            return Result.fail("不允许重复下单");
//        }
//        try {
//            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
//            return proxy.createVoucher(voucherId);
//        } finally {
//            //释放锁
//            lock.unlock();
//        }
//
//    }
    /**
     * 异步创建订单（由后台线程调用）
     */
    @Transactional
    public void createVoucherOrder(VoucherOrder voucherOrder) {
        // 注意：这里不再依赖 UserHolder！因为异步线程中 ThreadLocal 可能为空
        // 所有信息都从 voucherOrder 中获取

        // 1. 防御性检查：数据库是否已存在该订单（虽然 Redis 已去重，但兜底）
        Long count = Long.valueOf(query().eq("user_id", voucherOrder.getUserId())
                .eq("voucher_id", voucherOrder.getVoucherId())
                .count());
        if (count > 0) {
            log.warn("数据库已存在订单，跳过处理: userId={}, voucherId={}",
                    voucherOrder.getUserId(), voucherOrder.getVoucherId());
            return;
        }

        // 2. 扣减数据库库存
        boolean success = iSeckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0)
                .update();

        if (!success) {
            throw new RuntimeException("数据库库存不足，订单取消");
        }

        // 3. 保存订单
        save(voucherOrder);
    }
}
